A color filter on array (COA) technique includes manufacturing a color layer on an array substrate so as to form a color filter. FIG. 1 shows a basic structure of a COA substrate, where a thin film transistor (TFT), the color layer 4 and a pixel electrode 5 are sequentially formed on a base substrate 1, a protective layer 3 is arranged between a drain electrode 2 of the TFT and the color layer 4, a via-hole extending through the color layer 4 is arranged above the drain electrode 2, and the pixel electrode 5 is connected to the drain electrode 2 via the via-hole. For a display panel with the COA structure, it is unnecessary to align a color filter substrate with the array substrate, so it is able to reduce the difficulty in a procedure for arranging the color filter substrate and the array substrate opposite to each other to form a cell during the manufacture of the display panel and to prevent the occurrence of an error during the procedure. As a result, it is able to design a black matrix with a narrow line width, thereby to increase an aperture ratio.
Photolithography is used in the prior art to manufacture the COA substrate. In one way, after a RGB color layer is formed, a protective overcoat is applied onto the RGB color layer, so as to increase a thickness of the protective layer and replace a resin layer at a white pixel region. However, at this time, there is a relatively large segment difference between the white pixel region and a color pixel region. In another way, an exposing and developing process is required to be performed directly using a white resin material at the white pixel region. However, at this time, more materials and an additional process will be required, thus the production cost is increased.